1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a plasma display panel having an improved structure so that a light emission brightness and discharge efficiency can be improved.
2. Description of the Related Art
In general, an image is formed in a plasma display panel by generating a glow discharge by applying a predetermined voltage to electrodes in a state where a gas is filled between the electrodes, which are disposed in a sealed space, and exciting a phosphor layer that is formed in a predetermined pattern using ultraviolet rays generated during the glow discharge operation.
Plasma display panels can be classified into a direct current (DC) plasma display panels and alternating current (AC) plasma display panels according to their driving methods. In addition, the plasma display panel can be classified into a two-electrode type or a three-electrode type according to the number of electrodes they include. A DC plasma display panel includes an auxiliary electrode in order to induce an auxiliary discharge, and an AC plasma display panel includes an address electrode for improving address speed by a dividing address discharge and a sustain discharge. Also, an AC plasma display panel can be classified into an opposing discharge type and a surface discharge type according to the arrangement of the electrodes performing the discharge. The opposing discharge type AC plasma display panel includes two sustain electrodes forming the discharge disposed on two substrates respectively to generate the discharge perpendicularly to the panel, and the surface discharge type includes two sustain electrodes that are disposed on one substrate to generate the discharge on a surface of the substrate.
An AC plasma display panel having a general surface discharge type three-electrode structure is described as follows.
The plasma display panel includes an upper substrate on which an image is displayed, and a lower substrate disposed parallel to the upper substrate.
Pairs of sustain electrodes including common electrodes and scan electrodes are formed on a lower surface of the upper substrate. The common electrode and the scan electrode are separated from each other by a discharge gap (g). The common electrode includes a common transparent electrode and a common bus electrode formed on a lower surface of the common transparent electrode, and the scan electrode includes a scan transparent electrode and a scan bus electrode formed on a lower surface of the scan transparent electrode. The pairs of sustain electrodes are covered by an upper dielectric layer, and a protective layer is formed on a lower surface of the upper dielectric layer.
In addition, the lower substrate faces the upper substrate, and address electrodes are formed on an upper surface of the lower substrate perpendicularly to the sustain electrode pairs. The address electrodes are covered by a lower dielectric layer. Barrier ribs including longitudinal barrier ribs and transverse barrier ribs crossing the longitudinal barrier ribs are formed on the upper surface of the lower dielectric layer to define discharge cells in a matrix form. The barrier ribs are formed such that regions where the sustain electrode pairs and the address electrodes cross each other correspond to the discharge cells. In the discharge cells, red, green, and blue phosphor layers are selectively formed in order to realize colors, and a discharge gas is filled in the discharge cells.
In the plasma display panel having the above structure, the pairs of sustain electrodes can have various structures. The common transparent electrode of the common electrode and the scan transparent electrode of the scan electrode constituting the pair of sustain electrodes are formed as strips, and the common and scan transparent electrodes form the discharge gap (g) in the discharge cell. The discharge between the common and scan transparent electrodes starts at the discharge gap (g), and is diffused to the entire discharge cell.
In order to diffuse the discharge started at the discharge gap (g) into the entire discharge cell efficiently, the initial discharge should occur in wide area. However, when the discharge gap (g) has a predetermined width, the initial discharge occurs locally and the diffusion of discharge cannot be performed sufficiently. When the discharge is generated by applying voltages to the common and scan bus electrodes, a constant electric field is not formed between the common and scan transparent electrodes, and thus, unnecessary portion for the discharge increases in the common and scan transparent electrodes. The unnecessary portion lowers the discharge efficiency in the discharge cell, and blocks a large portion of the discharge cell, thereby lowering emission brightness.